AGROECOLOGY (بوم شناسی کشاورزی)
Year:2011 | Volume:3 | Issue:2|Papers Count:12

To compare the effects of different weed management methods on seed bank of weeds grown in sugar beet (Beta vulgaris L.), a field experiment was conducted at the Agricultural Research Station, Ferdowsi University of Mashhad, Iran, during 2006, 2007 and 2008. The experiment designed as a complete randomized block with three replications. The treatments including: disk+ fhenmedifham, disk+ fhenmedifham+ rotation, disk+ cultivation, disk+ cultivation+ rotation, metamitron+ fhenmedifham, metamitron+ fhenmedifham+ rotation, metamitron+cultivation, metamitron+ cultivation+ rotation, covercrop+ fhenmedifham, covercrop+ cultivation, weeding, weeding+ fhenmedifham and control. Soil samples were taken (in the base of clustering method) in two depths of 0-10 cm and 10-20 cm, at two stages, early season and late season. Results showed that at the first experiment highest and lowest seed bank size obtained in control plots (383 seeds per kg of soil) and weeding+ fhenmedifham (52 seeds per kg soil). At the second year maximum and minimum seed bank size were observed in control and weeding treatment with 1080 and 319 seeds/kg soil, respectively. In two years, seed bank size in 0-10 cm depth was more than 10-20 cm depth. In the first and second years seed bank size at late season compare to early season was 2.2 and 1.7 times, respectively. In two years, significant coefficients were observed in seed bank size at early season and late season (R2=0.76 and R2=0.65). There were significant correlations between seed bank size in the first and second year (R2=0.71) and between seed bank size and frequency of seedling (R2=0.77).

Crop residues management is one of the most important factors to sustain agro-ecosystems. Application of plant residues as organic fertilizers has functional role on the amount of soil elements, their availability for crops and finally yield obtained. In order to investigate the effect of different crop residues and their management on providing wheat potassium requirement, a four-replicated field experiment was carried out as a completely randomized block design on wheat (Triticum aestivum L.). Five plant residues with different C:N ratio (including cotton, soybean, alfalfa، wheat and corn) in companion with pure urea and control treatment (without residue or fertilizer) were incorporated as<5 mm particles seze. The rate of residues and required nitrogen factor to avoid immobilization were calculated by determinationof C:N ratio and nitrogen factor to provide 90 kg n.h-1. Soil extractable potassium was evicted by ammonium acetate extraction procedure after 49, 83, 99, 127, 165 and 175 days from beginning of experiment. The results showed that the effect of different residues on potassium release was significant just in booting growth stage. The highest concentration of K in booting stage belonged to alfalfa, wheat and corn residues (with corresponding values of 1663, 1637.6 and 1592.3 kg.ha-1 soil respectively) while the lowest values belonged to cotton residue, urea and control (1472.6, 1425.4 and 1215 kg.ha-1 soil, respectively). Assessing trend of potassium (K) uptake showed that the most K uptake in plants (36.62 g.kg-1) occurred during the first days (stem elongation) and in residue alfalfa treatment that the most K release (2375.7 kg.ha-1) was also from those residues. Therefore, it seems that crop residues could be considered as potential internal inputs for agro-ecosystems with different capabilities. Generally, our results revealed that alfalfa residue is the best option to provide potassium for wheat plants and corn and wheat (with not-significant difference) were ordered after alfalfa.

In order to study the effect of light quality and quantity on morphological and physiological characteristics of two late and early maize (Zea maize L.) S.C., an experiment was conducted in greenhouse conditions, Ferdowsi University of Mashhad, Iran, during 2008. The experiment was carried out factorial based on randomized complete block design with six treatments and three replications. Different light conditions including natural light, additional two hours lighting after sunset, and reduction of the quality and quantity of light conditions during plants growth, were investigated. The results indicated that leaf area in both maize hybrids increased by light measured until 28 days, and then decreased compared to the natural lighting conditions. In comparison with natural light conditions the dry mater of leaf and stem was increased by adding light until flowering stage. Leaf area and dry weight was reduced in both hybrids with decreasing lighting conditions. Leaf length to width ratio increased by adding the lighting measure till the seventh leaf appearance and later on reduced. This ratio increased with reduction of light duration. Chlorophyll content increased by adding light duration till the sixth leaf appearance. The chlorophyll content of two hybrids in screen conditions decreased compared to other conditions. In general, leaf area, stem and leaf dry weights, height and lodging index of short season hybrid was lower than long season hybrids. The present study showed that extending light duration resulted in increasing of the dry weight and development stage of maize.

Technique of remote sensing and its satellite products has many implementations in agricultural science and national resources. In this study، wheat yield in Esfahan province، Iran، were derived from MODIS satellite data over periods of 2000-2001(dry year) and 2004-2005 (wet year). For this purposes، 68 MODIS products of surface reflectance (MOD09GA) and land surface temperature LST (MOD11A2) over Esfahan in 8-day time step were collected. By using satellite data of LST and vegetation index NDVI، the amount of water stress during each time steps were estimated from a linear relation. Spatial distributions of active photosynthesis absorb radiation (APAR) were also estimated using NDVI index and meteorological data. Finally، cumulative dry matter as indicator of wheat yield was calculated using APAR، light use efficiency and water stress in each time. Actual biomass by using harvest index، converted to grain yield. The results indicated that the amount of dry matter in wet year (2004-2005) was 1.4 times of predicted production in the dry year (2000-2001). Isfahan city had the highest amount of increase and cities of Bigdel، Felavarjan، Ardestan showed the highest decrease in wheat yield production. Good trend of predicted yield with the observation data indicated a promise for application of this procedure for annual yield prediction before harvesting time in large regional scale.

Kochia (Kochia scoparia L. Schard) is an annual, halophyte and drought resistant plant, that it can be irrigated with saline water and a valuable source for forage under drought and saline ecosystems. In order to evaluate germination characteristics of kochia, an experiment was conducted during 2009 at Physiology laboratory of Ferdowsi University of Mashhad, Iran. This experiment was conducted in a completely randomized design with four replications. Germination was evaluated at 5, 10, 15, 20, 25, 30, 35 and 40oC under dark germinator with 50-60 percentage relative humidity. The results showed that the highest germination percentage was obtained at 20-30oC and the lowest obtained at 40oC. The longest and the shortest period to 20 and 50 germination percentages were recorded to 5-10oC and 20-30oC, respectively. The longest and the shortest period to 80 percentage germination were belonging to 15 and 30oC, respectively. Based on Five Parameters Beta model, base, optimum and ceiling temperatures for kochia estimated 3.4, 25 and 43.3oC, respectively. However, seed of this plant is able to germinate in wide temperature range.

This research was investigated to evaluate growth indices and competitive ability of two wheat (Triticum aestivum L.) cultivars in interference with two species of narrow and broad leaf weeds as two separated experiments based on a randomized complete block design with three replications at Agricultural Faculty of Bu-Ali Sina University, during 2008-2009. In both experiments, Alvand and Sayson cultivars were planted at 450 plants.m-2. In the 1st experiment, ryes (Secale cereale L.) with densities of 0, 20, 40, 60 and 80 plants.m-2 were planted between wheat rows. In the 2nd experiment, wild mustard (Sinapis arvesis L.) with densities of 0, 8, 16, 24 and 32 plants.m-2 were planted. Results showed that increasing plant density in both weed species led to reduction of leaf area index, dry matter accumulation, crop growth rate, leaf area index duration, biomass duration, and yield of wheat cultivars. Mentioned traits and grain yield of Alvand showed less decrease in competition with both weed species. Sayson plant height was decreased with increasing weed density but such observation was not found in Alvand cultivar. Individual plant damage of wild mustard on two wheat cultivars was more than that of rye. Overall، Alvand competability against both weed species was more than Sayson.

Russian knapweed (Acroptilon repens L.) is a perennial weed of Aceraceae that is becoming a dominant weed in suitable conditions. In order to find an ecological non-chemical approach for controlling Russian knapweed and studying the possibility of using flower-eater mite (Aceria acroptiloni Shevchenko & Kacalev) (Acarina: Eriophyidae), a series of studies including field survey and field experiments were conducted in North Khorasan province, Agricultural Research Station of Shirvan College during spring 2010. Preliminary studies included collecting, identifying and screening of insects as biocontrol agents for Russian knapweed were carried out. In field survey studies, contaminated natural regions by flower-eater mite were recognized. At the end of growing season, 20 health and infested plants were selected and their height, flower number, shoot fresh weight and shoot dry weight were measured afterwards. In the field experiment, 40 similar plants with about one meter away from each other were selected. In addition, 40 plants (20 infected and 20 healthy plants) were transplanted to the pots, and then planted in a land with a distance of about 100 cm. After establishment, control plants were sprayed with an acaricide 20 shoots each that used as ‘control’ and 20 shoots that infested with the mite were randomly selected. Russian knapweed shoots infested with the mite Aceria acroptiloni in a natural infestation were collected and observed under the binocular for the presence of the mite. The infested shoots were put in small vials filled with water, and transfer one shoot beside each of the 20 shoots that were selected for mite infestation. Mite infestation of the test shoots after two weeks was checked and in case the test shoots did not show signs of mite attack after four weeks, plants were infested again. As soon as the Russian knapweed leaves start wilting (when the green colour disappears), all 40 shoots were cut at the ground level. Each shoot put in a separate envelope، and the envelope labeled. In the laboratory, shoot height, fresh shoot weight, dry shoot weight, number of flower heads, numbers of seeds were recorded. The results showed that the mite did not feed from all plants except on Russian knapweed. Application of mite reduced the number of flowers by 68% in natural conditions. In the field conditions, it could reduce the number of flowers by 59% in the nature plants and 11% in transplanted plants. Since this mite was able to reduce vegetative and reproductive organs of Russian knapweed, it could be considered as a potential promising biological control agent for using in ecological agriculture.

The responses of isabgol (Plantago ovata Forsk.) to micronutrient foliar application under low irrigation condition were investigated. The experiment was carried out in Agricultural Research Farm of Zabol University, Iran, during growing season of 2007-2008. The experiment was conducted in spilt plot using randomized complete block design with four replications. Three irrigation regimes defined as normal irrigation, one time lack of irrigation before flowering and one time lack of irrigation after flowering were used as the main plots. Five levels of micronutrient foliar application including: control unit, four ppt of Fe, three ppt of Zn, four ppt of Mn, and a mixture of these elements were considered as subplots. The results indicated that the seed and biological yield, seed number per spike, spike number per plant and thousand seed weight were significantly affected by irrigation regimes. The maximum seed yield obtained in control plots with normal irrigation. The seed yield diminish in treatments of one time lack of irrigation before flowering and one time lack of irrigation after flowering was 14.9 and 20.1 percentage، respectively. The seed and biological yield, mucilage yield, seed number per spike and thousand seed weight were significantly affected by micronutrient foliar application. The maximum seed yield was observed in Zn treatment with 22.12% yield more than control. The maximum mucilage yield and percent were found in the treatment of one time lack of irrigation before flowering and the maximum turgid index in treatment of one time lack of irrigation after flowering. The micronutrient foliar application showed positive effect on seed, biological, and mucilage yields. The maximum seed yield was obtained in normal irrigation with micronutrient foliar application.

In this study tried to calculate attributed-based index and measurement of farmer’s attention to wheat (Triticum aestivum L.) seed environmental, cropping and marketing attribute and evaluate social– economical factors influencing on this index. After this estimation, effective factors have selected. Related data to 102 Mashhad wheat producers, Iran were used for estimations Poisson regression. Results showed that in seed characteristics set; marketability and taste were more important factors. Also, results of this study corroborant previews study and only variables age and family number make difference. Also, education, farming and non–farming income, farming experience, farm area and loan receive have positive effect on these characteristics.

In order to investigate the effect of Mycorrhizal fungi and phosphorus fertilizer on concentration of leaf nutrients and photosynthetic pigments of bean (Phaseolus vulgaris L.) in condition of irrigation with saline water, an experiment was conducted based on completely randomized design with three replications in greenhouse of Bahonar University of Kerman, Iran during 2010. The studied factors were water salinity (500 (control), 2000, 4000 and 6000 ms.cm-1), phosphorus fertilizer (0, 100 and 200 mg.kg-1 soil) in form of Triple super phosphate and mycorrhizal fungi with three levels (Glomus mosseae and Glomus intraradices and no fungi (control)). The results showed that the concentrations of chlorophyll a, chlorophyll b, total chlorophyll, carotenoeids, K, Ca and P were decreased with increasing of salinity levels. But salinity increased the concentration of Na and Na/K ratio. Mycorrhizal fungi had no significant effect on concentration of Ca and chlorophyll a. The interaction of salinity and phosphorus fertilizer on concentration of chlorophyll b, Na and P was significant. Results demonstrated that Glomus intraradices had better effect on improvement of photosynthetic pigments concentration and concentration of nutrition elements. In low levels of salinity stress, use of Mycorrhizal fungi with phosphorus fertilizer, can reduce the negative effects of salt by increasing of concentration of photosynthetic pigments and nutrition elements.

In order to study the effect of different organic fertilizers on quantitative and qualitative characteristics of fenugreek forage، an experiment was conducted based on completely randomized block design with six treatments and three replications at Agricultural Research Station, College of Agriculture, Ferdowsi University of Mashhad, Iran, during 2006. The experimental treatments were four organic fertilizers (40 t.ha-1 cow manure,  30t.ha-1 sheep manure, 20 t.ha-1 hen manure, and 30 t.ha-1 compost), chemical fertilizer (250 kg.ha-1 ammonium phosphate + 100 kg.ha-1 urea) and control (no-fertilizer). The results showed that there were no significant differences between different fertilizer treatments in terms of all quantitative and qualitative characteristics. However, the highest fresh forage yield (5618 kg.ha-1) and dry forage yield were obtained in using chemical fertilizer treatment. The highest leaf dry matter and organic matter digestibility and the lowest stem dry matter and organic matter digestibilities were produced in hen manure treatment. Chemical fertilizer treatment produced the lowest leaf dry matter and organic matter digestibility and the highest stem dry matter and organic matter digestibility. Generally, within studied fertilizers, chemical fertilizer had relatively higher effect on quantitative studied criteria.

In order to investigate the response of mycorrhizal fungi to different kinds of fungicides and phytohormone balance in soybean, the present study was carried out during 2008-2009 at Research Site of Azad University of Karaj branch as factorial based on randomized complete block design with two factors and four replications. Treatments were all combination of arbuscular mycorrhizal fungi species in four levels (Glomus mosseae, G. etunicatum, G. intraradices, control) and four fungicides [control, benomyl, Nano-silver and biologic (Bacillus subtilis)]. The results indicated that fungicides and mycorrhizal species had significant effect on phytohormons and mycorrhizal colonization. The mutualistic interaction between arbuscular mycorrhiza (AM) fungi and fungicide had significant effect on phytohormone changes. Gibberellin (GA), Auxin (AX) and cytokinin (CK) considerably increased in response to three species infection. G. intraradices inoculation brought about the largest increase (35.33%) in mycorrhizal colonization in comparison with control. The level of phytohormons significantly decreased in comparison with control by fungicide treatments. Mycorrhizal colonization decreased 44.12% by using Bacillus subtilis as biofungicide. AX, GA and CK concentrations decreased in AM-colonized plant when subjected to different fungicide treatments. Biofungicide had the most consistent effects towards G. intraradices and CK is found at about 2% higher in this treatment versus nonfoungicide-mycorrhizal treatment. AX, GA and CK tended to decreased 53.58%, 63% and 85.23% by inhibition effects of benomyl on G. etunicatum infection in comparison with nonfungicide control. By using nano-silver, G. mosseae showed more susceptibility than the other species. In conclusion, stimulating of phytohormons synthesis by mycorrhizal association decreased under fungicides stress.